The invention relates to silicon devices including a diode array target and to the selective growth of microcrystalline silicon pads for the diode arrays of such targets.
One type of silicon device is a silicon target for a vidicon type camera tube. Such targets are well known in the art and are described, for example, in U.S. Pat. No. 3,548,233 issued to E. F. Cave et al on Dec. 15, 1970. In the manufacture of such targets, one or more complicated and costly etching procedures, employing photoresist techniques, is required to produce an array of pads which is in registration with discrete regions of an underlying diode array. A simplified and less complicated manufacturing technique for such targets is desired.
One diode array target which may be manufactured by a simplified process to include an array of diodes having a self-registered conducting pad or overlayer by the hydrogen reduction of silicon tetrachloride is described in an article entitled "The Epicon Camera Tube: An Epitaxial Diode Array Vidicon" by S. M. Blumenfeld, G. W. Ellis, R. W. Redington and R. H. Wilson in IEEE Transactions on Electron Devices, Vol. ED-18, No. 11, November, 1971. Such targets include conducting pads for the diodes of the array which are the result primarily of single crystalline epitaxial growth. Unfortunately these pads produced by the hydrogen reduction of silicon tetrachloride include imperfections or variations in faceting of the crystalline structure which, because of the large crystalline size in excess of several microns, results in a variation in electron beam acceptance across the target's electron beam scanned surface. These imperfections or variations produce a distortion or noise in the image detected by the camera tube within which such a target is incorporated.
A target structure permitting simplified manufacture and having diode pads which do not include electron beam detectable imperfections is desired.